Why is insurance so high on the scion tc?

Because it's a car marketed at teenagers, designed to look fast, and for other reasons falls into the hands of guys who will really push it. Also, as it's been mentioned only Hummer drivers get more tickets than Scion drivers. The ironic thing is it shares an engine with the Camry, or at least the old Camry and so you really may as well just buy one of them.